Date of Award

Spring 5-24-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Micro and Nanoscale Systems

First Advisor

Matthew Hartmann

Comments

Memristors have gained a lot of excitement in academia and industry due to their electrical properties that could be leveraged in a variety of applications and technologies. As a fundamental electrical component alongside the resistor, inductor, and capacitor, the memristor is unique. Rather than coupling voltage and current (resistor), voltage and charge (capacitor), or current and magnetic flux (inductor), the memristor couples charge and magnetic flux. Even though the memristor’s fundamental unit is the same as the resistor—both are measured in ohms—the memristor can change its resistance based on the charge going through the device. This ability for resistive switching is combined with a non-volatility property where the memristor “remembers” its resistance even after the voltage is removed. Cobalt ferrite (CoFe2O4) is a material that has been explored in research to fabricate these devices. Like other ferrites, CoFe2O4 can form numerous oxygen vacancies that can be leveraged to form conductive filaments between two electrodes. The formation and destruction of these filaments enable memristive behavior. This work provides some of the first experimental results on the application of CoFe2O4 memristors. An active layer of CoFe2O4 was used with asymmetric electrodes of Ag and p++Si. This structure was evaluated and shown to have suitable memristive behavior for application in various fields. Here, these devices were utilized as resistive random-access memories (ReRAM). Then memristors were implemented in Chua’s circuit—the simplest analog circuit capable of exhibiting chaotic behavior—making this work the first experimental implementation of a ferrite memristor in an analog chaotic circuit. Two of these Chua’s circuits were then coupled together, allowing their chaotic behavior to synchronize, forming the basis for an encryption scheme. This scheme was shown to effectively encrypt and decrypt images, making this work the very first experimental implementation of physical memristors in coupled chaotic circuits. As the production of these devices is simple and inexpensive and the circuitry is easy to implement, this encryption scheme can quickly be used to increase the security of sensitive data alongside current encryption methods.

Download

Share

COinS